Technical Abstract:
Cryptosporidium parvum is a coccidial protozoan which infects intestinal epithelial cells in an broad variety of vertebrate hosts. The organism is recognized as a common cause of intestinal illness that can become chronic and severe in immuno-compromised hosts. Although several studies have documented the cellular and humoral immune responses in rodents, little information is available on the immune response of cattle during cryptosporidiosis. In the present study we investigated changes in expression of cell surface markers and cytokine mRNA in the ileo-cecal lymph nodes (LN), lamina propria (LPL) and intra-epithelial (IEL) lymphocytes of neonatal calves 7 days after a primary infection with C. parvum. Flow cytometric analysis of these populations showed very few mature cells in the mucosa but normal patterns in LN. After infection, significant increases were seen in the percentages of CD3+, CD8+ and IL2R+ cells only in IEL and LPL. Local cytokine responses were analyzed by competitive reverse transcriptase-polymerase chain reaction. Increases in the levels of IFN-gamma and IL12 (p40) mRNA were seen in LPL and IEL populations. No consistent differences were seen when mRNA was analyzed for IL10, and levels of mRNA for IL2 and IL4 in these three populations were very low and variable. In addition an increase in the levels of mRNA of the newly identified growth factor IL15 was observed in LPL.